Bacteria Species and Mechanisms (Pathophys) - Block 1 Flashcards
List G+ cocci
- Staphylococcus (aureus, epidermidis, saprophyticus)
- Streptococcus pyogenes (Group A)
- Streptococcus pneumoniae
- Strep agalactiae (Group B)
- Viridans strep
- Enterococcus (faecalis, faecium)
What makes are Staph similar?
Catalase + -> aerobic
What is the most pathogenic staph?
Aureus
Staphylococcus aureus
Differentiation, Location, Transmission, Disease
Differentiation:
* Catalase +
* Coagulase +
* G+
Location: skin, GI, GU
Transmission: person-person, direct, fomite
Dx: Toxin mediated, pyogenic
What are examples of toxin mediated dx?
Food poisoning, TSS, Scalded skin syndrome
What are examples of pyogenic dx?
Impetigo, folliculits, wound infection
What are the virulence factors of S. aureus?
- Encapsulated
- Teichoic acid (adhesion)
- MSCRAMMS -> biofilm
- Protein A that binds to IgG blocking complement binding
- Coagulase
- Lipases, hyaluronidase, fibrinolysin
- CYtotoxins (a, b, d, g)
- Exofoliative toxins (ETA, ETB)
- Enterotoxins (A to R)
- TSS toxin 1 (TSST-1)
What is the function of exofoliative toxins?
Serine proteases that breakdown the connections between stratum granulosum epidermis
What is enterotoxins?
Superantigens that stmulates T cell proliferation and release of cytkines and stimulates mediator release from mast cells -> nausea and vomiting
What is TSST-1?
Superantigen that stmulates T cell proliferation and release of cytokines and can cause endothelial leakage as well as cellular damage of endothelial cells
What is the difference between food-poisoning and foodbourne illness?
Food poisoning: preformed toxins that doesn’t require bacterial growth
Foodbourne illness: Requirs microbial growth within the host
How does the composition of MRSA diffferent from VRSA?
Meethicillin RSA: contains mecA gene that codes for PBP2a (lower affintiy for beta-lactams and methicillin)
Vancomycin RSA: contains van genes that change peptidoglycan precursors reducing vancomycin binding affinity
Staphylococcus epidermis
Differentiation, Location, Transmission, Diseases
Differentiation:
* Catalase +
* Coagulase -
* Urese -
* G+
Location: skin, conjunctiva, nose, GU
Transmission: person-person, direct, fomites
Dx: bacteremia, opportunistic
VF of S. epidermidis
- Encapsulated
- Slime layer
- Cytotoxin (delta)
Staphylococcus saprophyticus
Differentiation, Location, Transmission, Diseases
Diff:
* Catalase +
* Coagulase -
* Urease +
* G+
Location: perineum, rectum, urethra, cervix, GIT
Trasmission: sexually active females and catheters
Dx: Dysuria, pyuria
VF of S. saprophyticus
- Urease
- Non-hemolytic
Staph that has B-hemolysis?
Aureus
Staph’s response to mannitol salt agar?
Aureus: yellow colonies
Epidermis: pink/white
What staph presents with a + urease?
Saprophyticus
What Staph is coagulase +? -?
+: aureus
-: epidermis, saprophyticus
What are the common characteristcs of Streptococcus?
SOD+, catalase +
What is Strep calassified
- Lancefield groupings
- Hemolytic patterns
Streptococcal pyogenes
Classifications, Location
Classification:
* Group A
* b-hemolytic
Location: Upper respiatory, GUT
VF of Streptococcal pyogenes?
- Hyaluronic acid capsule
- M protein
- Adhesions
- C5a peptidase
- Hyaluronidase and streptokinase
- Cytotoxins (Steptolysin S and Streptolysin O)
- Streptococcal pyrogenic exotoxin
Streptococcus pneumoniae
Classifications, Location, Transmisson, Diseases
Classifications:
* No cell wall
* a-hemolytic
* Facultative anarobe
* diplococci
Location: upper resp
Transmission: respiratory droplets
Dx: otits media, CAB pneumonia
VF of S. pneumoniae
- Capsule
- IgA protease
- H2O2
- Pneumolysin
Streptococcus agalactiae
Classifications, Locaton, Diseases
Classification:
* Group B
* Capsule
* B-hemolytic
Location: UT, GIT
Dx: Neonatal sepsis, pneumonia, meningitis, and bacteremi
Viridans streptococci
Classifications, Location, Disease
Classification:
* Green pigment colonies
* Non-capsulated
* Catalase -
* a-hemolytic/nonhemolytic
Location: oropharynx, GI, GU
Dx: dental infection, endocarditits
Enterococcus
Classification, Location, Transmission, Disease
Classification:
* Group D
* Facultative anaerobes (catalase -)
* Oxidase -
* E. faecalis: gamma non-hemolyic
* E. faecium: a-hemolyic (MDR)
Location: GI
Transmission: nosocomial, patient-patient
Dx: UTI
VF of enterococcus?
Biofilms
G+ bacilli that form spores?
Bacillus and clostridium
G+ bacilli that don’t form spores
Corynebacterium, Listeria
Bacillus cereus
Classification, Location, Disease
Classification:
* Spore forming
* Opportunisitc
* B-hemolytic
* Facultative anaerobe
* Catalase +
* Oxidase -
Location: from contaminated soil
Disease: Gastroenteritis, ocular infection
What are the types of enterotoxins produced by Bacillus cereus?
Heat stable: , proteolysis-resistant toxin causes emetic form of disease -> food poisoning
Heat labile: enterotoxin causes the diarrheal form -> foobourne
Costridium perfrigens
Classification, Location, Disease
Classification:
* Capsulated
* Non-motile
* SPore forming
* B-hemolytic inner zone, a-hemolytic outer
* Obligate anaerobe (catalase -)
Location: GI
Dx: soft tissue infections
VF of costridium perfringens?
- Enzymes: collagenase, proteases, and hyaluronidase
- Cytotoxin: phospholipase C lyses host cells
- Enterotoxin and can cause food poisoning
- Fermentation -> gas gangrene
Clostridioides (Costridium) difficile
Classification, Location, Disease
Classification:
* Anaerobic
* Spor forming
* Dysbiosis
Location: GIT
Disease: CDAD, PMC
How does C. diff become infectious?
- Produces toxin A (excessive fluid secretion) and B (cytotoxin)
- Occurs in stationary phase
- ID’d by ELISA in fecal sample
What are the large G+ bacilli?
- Bacillus cereus
- Costridium perfrigens
- C. diff
Listeria monocytogenes
Classification, Location, Disease
Classification:
* Catalase +
* weakly b hemolytic
* Facultatitve intracellular anaerobe
Location: Laboratory testing: gram stain of sterile samples (blood/CSF) and culture on blood agar
Dx: listerosis, menigitis, pregnant femal, neonates, elders, ICU
Describe how listeria is incorporated into the body?
- Adheres to enterocytes by listeria adhesion protein and internalin A
- Produces cytolysisns that allows it to escape phagolysosome to cytosol
- Multiples move to cell membrane to go to another cell (infected cell dies)
- Listeria is taken up by phagocytosis and distributed in the body
- Penetrates microglia and neurons in CNS
Corynebacterium diphtheriae
Classification, Disease
- Facultative anaeobes
- COntagious through resp drops, direct contact, fomites
- Releases diptheria toxin
Dx: diptheria, pharyngitis, endocarditis
What is the mechanism of diphtheria toxin?
- Exopoxin is produced when lysogenized by bacteriophage carrying the toxin gene
- Creation of pseudomembran in throat -> respiratory obstruction -> toxemia
How can you prevent Corynebacterium diphtheriae infection?
DTaP toxoid vaccine
Nocardia
Classification, Location, Transmission, Disease
Classification:
* partially acid fast
* Mycolic acid
* Strict aerobe
* Catalase +
* SOD +
* Blocks acidification of lysosome in order to replicate and survive
Location: lungs, skin, brain
Transmission: Inhalation, trauma
Dx: pulmonary, cutaneus, CNS infections
What are the small G+ bacilli?
- Listeria
- Corynebacterium diphtheriae
Examples of branching G+ bacilli?
Nocardia
VF of Neisseria
- Lipooligosaccharide (LOS, endotoxin) lack the repeating O antigen
- Encampsulated
- IgA protease
- Pili
What are the common characteristics of Neisseria?
- Obligate aerobe
- Fastidious
- Oxidase +
- Catalase +
Neisseria menigtides
Location, Transmission, Disease
Location: nasopharynx
Transmission: respiratory droplets
Disease: CAB meningitis
* Conjugate meningococcal vaccine is available
What is the 2nd most common STI?
N. gonorrheae
Neisseria gonorrhoeae
Location, Transmission, Disease
Location: vagina, urethral, rectal, oral
Transmission: vertical, horizontal (sex)
Disease: gonorrhea or related PID
* Sticky purlent discharge
VF of N. gonorrhoeae
Pili for adherence
What are you G- cocci?
Neisseeria:
1. menigitides
2. gonorrhoeae
Moraxella catarrhalis
Classification, Location, Disease
Classification:
* Oxidase +
* Catalase +
* Obligate aerobe
* Non-motil
* LPS endotoxin
* B-lactamases
Location: Upper respiratory tract
DIsease: sinusitis, otitis media infection
Haemophilus influenzae
Classification, Location, Disease
Classification:
* Facultative anaerobes, catalase +, oxidase +
* Pleomorphic, thick capsule
* 6 caqpsular serotypes exist
* Fastidious
Location: upper respiratory tract (throat)
Transmission: respiratory droplets
Dx: pneumonia, meningitis
What bacteria is the leading cause of bacterial meningitis?
Haemophilus influenzae
VF of Haemophilus influenzae?
- IgA protease
- Hib capsule
- endotoxin
- pili
What are you G- coccobacilli?
- Moraxella
- Haemophilus influenzae
Aeromonas
Classification, Location, Disease
Classification:
* Lactose fermenter
* Catalase +
* Oxidase +
Location: brackish water, contaminated food
Disease: dysentery, cellulitis, opportunistic infection
VF of thee Aeromonas?
- Adhesion (flagella, pilli)
- Hemolysins
- Siderophores
- Endotoxin
- Enterotoxins
- MDR
Vibrio
Classification, Location, Transmission, Disease
Classification:
* Lactose ferementer
* Oxidase +
* O-antigen
Location: GI mucous membrane
Transmission: Fecal-oral food and water
Disease: Vibrio cholerae
Bacteria that cause rice water stool?
Vibrio
Describe the characterisitcs of the cholera toxin?
Rice water stool -> dehydration:
1. B part of toxin binds to GI epithelial cells
2. A part enters cells to increase cAMP levels -> active secretion of ions from cell
Escherichia coli
Classification, Location, Disease
CLassification:
* faculatative anaeerobe
* Catalase +
* Oxidase -
* Fermenter of glucose and lactose
* O antigen
Location: GIT
Disease: opportunistic, water diarrhea, dysentery
VF of E coli?
- Capsule and fimbriae to adhere to mucosal surfaces
- Hemolysins
- Siderophores
- Enterotoxins
- Motile due to flagella
How can MacConkey detect lactose fermenters?
Pink colonies
What E.coli strain is a major cause of UTI in healthy individuals?
UPEC
What E. coli stain produces enterotoxins that cause diarrhea without destroying the cells of the intestines?
ETEC
* traveler’s diarrhea
* heat stable enterotoxin and heat labile enterotoxin
* Fecal oral from contaminated food
What E. coli strain destroys intestinal lining, kidney failure, and hemolytic uremic syndrome?
Enterohemorrhagic (EHEC) 0157:H7 E. coli
* produces shiga toxin -> inhibits protein synthesis
* Abdominal cramps, diarrhea, fever, vomiting
* Causes severe foodborne disease from raw food
Klebsiella
Classification, Location, Transmission, Disease
Classification:
* faculative anearobe
* Oxidase -
* Lactose fermenting
* Urease +
Location: GI and GUT
Transmission: Horizontal
Disease: Pneumonia, UTI, wound infection, sepsis, alveolar necrosis, nosocomial infection
VF of Klebsiella
- Fimbriae
- Siderophores
Eneterobacter
Classification, Location, Transmission, DIsease
Classification:
* facultative anaerobe
* Oxidase -
* Motile
* Feremtner
* Urease +
Location: GIT
Transmission: Horizontal
Disease: nosocomial
VF of Enterobacter?
- Fimbriae
- LPS
- Capsule
- Hemolysins
- Siderophores
Citrobacter
Classification, Location, Disease
Classification:
* Facultative anaerobe
* Oxidase -
* Lactose-fermenting, use citrate as carbon source
* Motile (flagella)
Location: GIT and soil
Transmission: Vehicle from contaminated food
Disease: diarrhea, UTI, pneumonia, nosocomial infection (shiga toxin)
VF of Citrobacter?
- Flagella
- LPS
- Shiga toxin
Campylobacter jejuni
Classification, Location, Transmission, Disease
Classification:
* Microaerophile
* Oxidase +
* Urease -
* Non-fermenter
Location: GIT
Transmission: animals to humans by fecal oral route, COntaminated meat, milk, water
Dx: foodbourne illness, dysentery
VF of Campylobacter jejuni?
- Adhesion
- Cytolysins
- Hemolysins
Helicobacter pylori
Classifcation, Location, DIsease
Classification:
* Enteric GNR
* Motile
* oxudase +
* Non fermenter
* Catalase -
* Urease
Location: Lower stomach, intestines
Disease: acute and chronic gastritis, peptic ulcers, and gastric cancer
Pseudomonas aeruginosa
Classification, Location, Disease
Classification:
* Polar flagella
* Obligate aerobe
* Catalase +
* Oxidase +
* b-hemolytic
* Non fermenter
Location: soil and moist reservious
Dx: Opportunistic
What type of bacteria is green in color and grown on blood agar?
Pseudomonas aeruginosa
VF of Pseudomonas aeruginosa?
- Flagella
- Pilli
- Exotoxins
- Proteases
- b-lactamases
What are your non-enteric G- bacilli?
- Pseudomonas aeruginosa
- Acinetobacter
- Bordetella
- Legionella
What are you enteric GNR G- bacilli?
- Serratia
- Proteus
- H. pylori
- Klebsiella
- Enterobacter
- Citrobacter
What are your GI G- bacilli?
- Campylobacter jejuni
- Salmonella
- Shigella
Serratia
Classification, Location, Disease
Classification:
* enteric
* Oxidase -
* Non feremetner
* Motile
Location: UT, lower respi
Disease: Opportunistic and nosocomial pathogens, UTI, lower resp infection
Proteus
Classification, Disease
Classification:
* enteric
* Oxidase -
* Non feremetner
* Motile
* urease +
* Causes formation of insoluble phosphates and magnesium stones (struvite stones
Disease: Nosocomial UTI
Salmonella enterica
Classification, Location, Transmission, Disease
Classification:
* Faculative anaerobes
* Non fermenter
* Catalase +
* Oxidase -
Location: Attach to mucosa in small intestine and enter enterocytes and Peyer patches and be transported into the blood or lymph
Transmission: eating contaminated food or by fecal-oral spread
Dx: Dysentery, enteric fever (typhoid)
VF of Salmonella
Can survive in macrophages, neutrophils and DCs and spread from the intestine to other body sites or blood
* Release typhoid toxin -> cell senescence allowing bacteria to hide and replicate
Shigella sonnei
Classification, Location, Transmission, Dx
Classification:
* Non motile
* Facultative anaerobes
* No fermentation or oxidase
Location: GIT
Transmission: fecal contaminated food
Dx: FBI, dysentery
VF of shigella sonnei
- Invades and destroys the mucosa of large intestine -> dysentery
- Exotoxin with enterotoxic and cytotoxic properties fro shiga toxin -> inhibits protein synthesis
- Reproduce intracellularly with invasins
- O antigen of LPS
Bordetella pertussis
Classification, Disease
Classification:
* Encapsulated
* Aerobic, oxidase +
* Fimbraiae
Disease: upper respiratory infection, pertussis
* Vaccine- TDaP
Acinetobacter
Classification, Disease
Classification:
* Obligate aerobe
* Oxidase -
* Opportunisitc
Disease: Nosocomial wound and pulmonary infections
Legionella
Classification, Transmission, Disease
Classification:
* Aerobic
* Uncap
Transmission: aerosolized water
Dx: Respiratory infection
VF of Legionella
- Chlorine tolerant
- Intracellular pathogen: blocks lysosome while replicating in macrophages
What are the nosocomial pathogens that exhibit MDR?
- Enterococcus faecium
- Staphylococcus aureus
- Klebsiella pneumoniae
- Acinetobacter baumannii
- Pseudomonas aeruginosa
- Enterobacter spp
- E. coli
What are spirochetes?
- Slender and tightly coiled bacteria
- Visible by darkfield microscopy not by Gram stain
- Move by using periplasmic flagella
- Protoplasmic cylinder
What are the types of atypical spirochetes?
- Treponema
- Borrelia
- Leptospira
Treponema pallidum
Classification, Transmission, Disease
Classification: Atypical spirochetes
Transmission: Direct contact on lesions of skin and mucous membranes
* Vertical
Dx: syphilis
How does Terponema enter the body?
- enters through breaks in mucosal membranes and skin
- Prefers to grow in lower temperatures so lesions are found on lips, tongue, and genitalia
- Spreads through blood and lymph
- Fastidious and fragile
What enzyme is produced by Treponema?
Hyaluronidase
Borrelia burgdorferi
Classification, Location, Transmission, Disease
Classification:
* No toxins
Location: Spread from the site of the tick bite to the surrounding skin
Transmission:
* Reservoir is small mammals
* Transmitted by arthropod bites
Disease: Lyme and relapsing fever
What are the stages of Lyme?
1: spread from the site of the tick bite to the surrounding skin
2: 2-cardiac and neurologic involvement (weeks-months)
3: Arthritis
Describe the life cycle of borrelia?
How do atypical bacteria differ from other groups?
- No typical G stain
- Facultative intracellular bacteria can replicate inside or outside of host
- Facultative intracellular bacteria can replicate inside or outside of host
What bacteria invade host cells as a means of protection from the immune system?
Mycobacterium, Mycoplasm
What bacteria utilizes host’s cellular machinery to replicate?
Chlamydia, Rickettsia
How does mycoplasma differ from other atypicals?
Lack a cell wall
* Bound by a cell membrane lacking peptidoglycans
* Contains lots of sterols in membrane
Disease acquired from Mycoplasma?
Community-acquired walking or atypical pneumonia
How does Mycobacterium differ from other bacteria?
- Strictly aerobic and have slow generation times
- Contains Mycolic acid therefore can use an acid fast stain to ID
Mycobacterium tuberculosis
Classification, Trasmission
Classification: Atypical that causes TB, obligate aerobe
Transmission: Respiratory droplets
Describe the mechanism of m. tuberculosis?
- Inhibits phagolysosome
- Causes a delayed type hypersensitivity resulting in formation of destructive multinucleate giant cells and granulomas -> destroying lung tissue
- Granulomas develop when there is continuous activation of macrophages
- Granulomas release large amounts of lytic enzymes that damage blood vessels and lead to tissue necrosis–granulomatous response.
- Can cause latent infection
Describe the characteristics of Chlamydiae?
- Obligate intracellular atypical
* Rely on host to make ATP (energy parasites)
* Block fusion of the phagosome with the lysosome
* Have a rigid cell envelope with 2 lipid bilayers with LPS, but with no peptidoglycan
Disease caused by Chlamydiae?
Chlamydia that can cause urethritis (discharge and pain with urination), cervicitis, and conjunctivitis (can lead to corneal scarring)
* Asymptomatic in females
* Symptomatic in males
What bacteria utilizes elementary body?
Chlamydiae
Describe the life cycle of chlamydiae?
- EB attaches to receptor on host cell
- EB enters host cell by endocytosis
- EB converts into RB in vesicle
- RB undergoes binary fission producing inclusion bodies
- RB udergoes more binary fission to form EBs
- EBs are released from host and infects others
How is Rickettsia trasmitted?
arthropod vector (deer and dog ticks)
Dx caused by Rickettsia?
Rocky mountain spotted fever:
* Vascularitis, endothelial damage, edema
* arthropod vector (deer and dog ticks)